1. Technical Field
The present invention relates to touch sensing apparatus and method, and more particularly, to touch sensing apparatus and method capable of supporting hover sensing which can sense both a touch event and a hover event.
2. Description of the Related Art
A touch screen is rapidly replacing apparatuses of a button input type due to the convenience and simplicity of use. The touch screen is classified into a resistive type and a capacitive type depending on a method of sensing a touch. These methods each have their advantage and disadvantage. Herein, since the capacitive type has high durability and detects a multi touch, the capacitive type has more frequently been used than the resistive type.
The capacitive type is a type which converts a value of a capacitor changed when a touch panel is touched by a user's hand or a touch pen into a voltage and converts the voltage into a digital to determine whether the touch panel is touched. A method of electrically converting the value of the capacitor into an electrical signal has been also researched variously.
In particular, a method of using an integrator converts and outputs a capacitance of the capacitor into a voltage several times. In this case, the method of using an integrator is relatively more robust against noises than a method of converting a capacitance of a capacitor into a voltage only once, and therefore has been frequently used.
Meanwhile, the touch screen panel is operated by being mounted in a display device, such as a liquid crystal display (LCD) and an organic light emitting display (OLED). In this case, a malfunction may occur at the time of sensing a touch, due to noises introduced from the display device. Further, a circuit (integration circuit) for measuring capacitance may be wrongly operated due to a common noise, such as a power supply noise and an electromagnetic wave noise introduced from the air, an instantaneous noise introduced from a touch pen or a user's hand at the time of touching the touch screen panel, and the like. Further, there is a limitation in increasing a gain of an integrator due to the common noise, and the like, such that it is difficult to support hover sensing capable of sensing a hover event which can detect objects which are present in the vicinity of a touch sensor but are not touched.
Patent Document disclosed in the following Prior Art discloses improved capacitive type touch and hover sensing using a sensor array. The following Patent Document includes an AC ground shield, which is disposed behind the sensor array and is stimulated with a signal having the same waveform as a signal driving the sensor array, to concentrate an electric field extending from the sensor array so as to increase a sensing range of the sensor array, thereby improving the hover sensing capability. However, the following Patent Document has a problem in that since there is a need to dispose a separate AC ground shield behind the sensor array and apply the same signal as the signal driving the sensor array to the AC ground shield so as to improve the hover sensing capability, a manufacturing process of the touch panel may be complicated.
Therefore, a need exists for a touch sensing apparatus which can simultaneously support the touch and hover sensing without needing to perform an additional manufacturing process of a touch panel, accurately sense the touch and hover event, and be operated in analog mode or a digital mode.